I used this on my outboard and it measured 60-30 psi. So I borrowed a tester and it read 176-174 psi. So I would have had possibly scrapped motor due to bad compression. Good thing I tested again with a accurate tester. To make things worse Harbor Freight charged me 20% restock fee for their defective tools. 100 percent satisfaction guaranteed as long as you pay restock fee.
Tip for consumers: 20% restock fee on defective is ridiculous